1. Field of Invention
The present invention relates to a transistor structure, and more particularly to a junction field effect transistor (JFET) structure with the high-voltage resistant characteristic.
2. Description of Related Arts
The junction field effect transistors (JFETs) are often used in the power chip. JFET is a unipolar three-layer transistor and a field effect transistor whose control electrode is made up of PN junction. It depends on the movement of a current carrier such as electrons or holes. For a normal operating device, when the drain-to-source voltage of the N-channel JFET is positive, or the drain-to-source voltage of the P-channel JFET is negative, the current passes through the channel. The current in the channel of the JFET is controlled by the grid voltage. To pinch off the flow of the current, the grid-to-source voltage of the N-channel JFET must be negative; or the grid-to-source voltage of the P-channel JFET must be positive. The grid voltage is applied to the channel across the PN junction in the JFET. On the contrary, the grid voltage is applied to the insulator in the MOSFET.
In practical applications, a JFET structure with the high-voltage resistant characteristic is needed. Therefore, it is necessary to provide a new JFET structure with the high-voltage resistant characteristic as required.